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Insect Structure

Insect Structure. Why Study?. An understanding of the external structure of the insect is necessary… - to allow the identification of insects and other arthropods - to understand their biology and control. Exoskeleton. Outer layer or “skin” Functions:

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Insect Structure

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  1. Insect Structure

  2. Why Study? • An understanding of the external structure of the • insect is necessary… • - to allow the identification of insects and other arthropods • - to understand their biology and control

  3. Exoskeleton • Outer layer or “skin” • Functions: • - Protection of soft parts • - Muscle attachment • - Support • - Site for sensory organs • - Helps prevent desiccation • - Reduces pathogen entry

  4. Components of the Exoskeleton • Cuticle • - non-living • Epidermis • - living • - secretes the cuticle • Basement membrane • - non-living • - function not known

  5. Cuticle • Key contributor to the success of insects • - barrier between living tissue/environment • - restriction of water loss • - abrasion protection cement wax epicuticle exocuticle cuticle endocuticle

  6. Body Structure • 3 body regions • 1 pair of antennae • 3 pair of legs on the thorax Head Thorax Abdomen

  7. Head • Functions: • - Mouthparts (feeding appendages) • - Sensory organs (interaction with nature) • - photoreceptors/vision • - receptors on antennae • - Houses the brain

  8. Antennae • Single pair • Located between and in front of eyes • Sensory function • - touch • - smell • - humidity • - sound

  9. Antennae • Types

  10. Vision • Compound eyes • - main organ of vision • Composed of individual units - ommatidia • - each registers a portion of a mosaic image • - number vary (>25,000 for dragonflies) • - surface of eye is protected with a cuticle • Resolution of image varies • - dragonfly: several meters away • - other insects: only a meter or so away

  11. How do insects perceive the world? • Many can see color (but many blind to red) • Others see colors we can not - Ultraviolet • Some only detect degrees of light and no image • Others are totally blind

  12. Nectar Guides • Many insect-pollinated flowers have nectar guides • Serve as visual guides to direct insects to nectar source • Nectar guides absorb UV light • Rest of flower reflects UV light

  13. Mouthparts • Basic types: • - chewing - sponging • - piercing-sucking - siphoning • - rasping-sucking - chewing-lapping • Important for insect identification • Provides information on feeding habits and types of damage

  14. Chewing Type • Simplest type • Used to chew holes in leaves, bore in stems • Examples: grasshoppers, crickets, • caterpillars, beetles

  15. Piercing-Sucking Type • Common and important type • Greatly modified for puncturing • plants and animals • Mouthpart components form needle-like stylets • Capable of transmitting viruses • Toxic saliva • Examples: mosquitoes, stink bugs, etc.

  16. Rasping-Sucking Type • Combination of chewing and piercing-sucking • Rasp (scrap) surfaces of leave, suck up sap • Example: thrips

  17. Sponging Type • Modified for liquids or solid foods • - solid foods must be dissolved by salivary • secretions • Example: house fly

  18. Siphoning Type • Mouthparts form a sucking tube (proboscis) • - modified for uptake of nectar/liquids • Coiled beneath head when not in use • Examples: butterflies and moths

  19. Chewing-Lapping Type • Modified to use liquid or semi-liquid foods • Some mouthpart components function for chewing • - mold wax • - grasping prey • - cutting flowers • Other components form the proboscis • - ‘lapping’ surface • Examples: honey bee, bumble bee

  20. Thorax • Divided into 3 regions • - prothorax • - mesothorax • - metathorax • Main function: locomotion • - walking/running • - jumping • - swimming • - flying

  21. Legs • Three pairs of true legs • 6 basic segments of the leg • - coxa • - trochanter • - femur • - tibia • - tarsus • - pretarsus • Adapted for various functions

  22. Types of Legs • Cursorial – running • Fossorial – digging • Raptorial – predaceous • Saltatorial – jumping • Natatorial - swimming

  23. Wings • Number of wings varies by species • - 2 pairs • - 1 pair on the mesothorax • - absent • Functions • - locomotion • - protection • - camaflouge

  24. Types of Wings • Membranous • Elytra - hardened, front wings that serve as protective covers for membranous hind wings • Hemelytra - front wings that are leathery or parchment- like at the base and membranous near the tip • Halteres - small, club-like hind wings that serve as gyroscopic stabilizers during flight • Scales • Tegmina - front wings that are completely leathery or parchment-like in texture

  25. Abdomen • Functions: • - respiration • - excretion • - reproduction

  26. Abdomen • Spiracles • - openings involved in respiration • - located on each side of abdomen • Cerci • - sensory organs • Ovipositor • - egg-laying structure • - stingers (modified ovipositor • found in some females)

  27. That’s All!!!

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